Rain and hail can reach the surface of Titan

S. D B Graves, C. P. McKay, Caitlin Griffith, F. Ferri, M. Fulchignoni

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

We have calculated the condensation and evaporation of ternary CH4-N2-C2H6 liquid drops and solid CH4 hail as they fall through Titan's lower atmosphere to determine the likelihood that precipitation reaches the ground. Assuming the humidity profile determined by the Huygens probe, binary liquid CH4/N2 condensate grows in the region from ∼8 to 15 km in Titan's atmosphere because the combined humidity of CH4 and N2 exceeds saturation. These drops evaporate below ∼8 km. We determine the fate of 10 μm seeds composed of ethane, which is expected to provide condensation sites. In addition, we study the fate of already formed raindrops with radii of 1-4.75 mm falling out of the growth region. High (50%) and low (0%) ethane relative humidities (RH) are considered in the calculation. We find that drops with radii ∼3 mm and smaller dropping from 8 km reach the ground in compositional equilibrium with the atmosphere in the high ethane RH case as a result of the stabilizing influence of the ethane, and evaporate in the atmosphere in the low ethane RH case. Large drops (>∼3 mm) reach the surface large and cold because the latent heat loss due to the evaporation of methane cools the drop and slows the evaporation rate. Pure methane hail hits the ground if its radius is initially more than 4 mm at 16 km above the surface and sublimates in the atmosphere if its radius is smaller.

Original languageEnglish (US)
Pages (from-to)346-357
Number of pages12
JournalPlanetary and Space Science
Volume56
Issue number3-4
DOIs
StatePublished - Mar 2008

Fingerprint

hail
Titan
ethane
rain
humidity
atmosphere
relative humidity
radii
evaporation
atmospheres
condensation
methane
Huygens probe
sublimate
raindrops
Titan atmosphere
lower atmosphere
liquid
evaporation rate
raindrop

Keywords

  • Hail
  • Huygens
  • Methane
  • Rain
  • Titan

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Graves, S. D. B., McKay, C. P., Griffith, C., Ferri, F., & Fulchignoni, M. (2008). Rain and hail can reach the surface of Titan. Planetary and Space Science, 56(3-4), 346-357. https://doi.org/10.1016/j.pss.2007.11.001

Rain and hail can reach the surface of Titan. / Graves, S. D B; McKay, C. P.; Griffith, Caitlin; Ferri, F.; Fulchignoni, M.

In: Planetary and Space Science, Vol. 56, No. 3-4, 03.2008, p. 346-357.

Research output: Contribution to journalArticle

Graves, SDB, McKay, CP, Griffith, C, Ferri, F & Fulchignoni, M 2008, 'Rain and hail can reach the surface of Titan', Planetary and Space Science, vol. 56, no. 3-4, pp. 346-357. https://doi.org/10.1016/j.pss.2007.11.001
Graves, S. D B ; McKay, C. P. ; Griffith, Caitlin ; Ferri, F. ; Fulchignoni, M. / Rain and hail can reach the surface of Titan. In: Planetary and Space Science. 2008 ; Vol. 56, No. 3-4. pp. 346-357.
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